1. Field of the Invention
The present invention relates to an apparatus for displaying tool vectors of a tool in a machine tool with rotational axes and, more particularly, to a tool vector display apparatus used for a machine tool to display a line segment connecting between a tool center point and a point on the central axis of the tool at a certain distance away from the tool center point, as a tool vector, on a path of the tool center points.
2. Description of the Related Art
Some currently-used numerical controllers for controlling machine tools have a function to display a commanded path or a function to display a path on which the tool actually has moved. For example, Japanese Patent Application Laid-Open No. 7-72914 discloses a tool path display apparatus for CAD/CAM systems that displays a three-dimensional path of the tool center points and changes the color or width of lines according to the tool speed.
In a 5-axis machine tool, which includes rotational axes, the orientation of the tool changes in various directions during machining. A workpiece may be machined by the tool side rather than the tool end, so the relation between the machined surface and the motion of the tool cannot be sufficiently verified only from the tool end path.
FIGS. 1A and 1B illustrate effects of the inclination of the tool. Even when the position of the tool center point of a tool 23 remains unchanged, the actual cut surface of the workpiece changes depending on the inclination of the tool 23, as clear from the comparison of FIG. 1A with FIG. 1B. FIGS. 2A and 2B illustrate that when the tool 23 inclines in machining by a side of the tool 23, the cut surface is affected. When a workpiece is machined by a side of the tool 23 as shown in FIG. 2A, the inclination of the tool 23 affects the cut surface. In FIG. 2B, the inclination of the tool 23 is represented by a tool vector and tool vectors are indicated along the path of tool center points to indicate that when a tool vector inclines, the cut surface of the workpiece is affected.
A technique for displaying tool vectors using data created by CAD or the like is disclosed in, for example, Japanese Patent Application Laid-Open No. 7-72914. However, this technique does not use actual feedback information, so comparison with machining failure points on a workpiece is not possible and thereby this technique is not useful for adjusting a 5-axis machine tool or finding the places of failures.